git branch -m が worktree の HEAD を更新するようになる diff

git.diff

diff --git a/builtin/branch.c b/builtin/branch.c
index 7b45b6b..07b7afb 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -20,6 +20,7 @@
 #include "utf8.h"
 #include "wt-status.h"
 #include "ref-filter.h"
+#include "worktree.h"
 
 static const char * const builtin_branch_usage[] = {
 	N_("git branch [<options>] [-r | -a] [--merged | --no-merged]"),
@@ -552,8 +553,7 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 	if (recovery)
 		warning(_("Renamed a misnamed branch '%s' away"), oldref.buf + 11);
 
-	/* no need to pass logmsg here as HEAD didn't really move */
-	if (!strcmp(oldname, head) && create_symref("HEAD", newref.buf, NULL))
+	if (update_all_worktree_head_symref(oldref.buf, newref.buf))
 		die(_("Branch renamed to %s, but HEAD is not updated!"), newname);
 
 	strbuf_addf(&oldsection, "branch.%s", oldref.buf + 11);
diff --git a/worktree.c b/worktree.c
index 6181a66..e712150 100644
--- a/worktree.c
+++ b/worktree.c
@@ -217,3 +217,40 @@ char *find_shared_symref(const char *symref, const char *target)
 
 	return existing;
 }
+
+int update_all_worktree_head_symref(const char *oldref, const char *newref)
+{
+	int error = 0;
+	struct strbuf path = STRBUF_INIT;
+	struct strbuf ref_target = STRBUF_INIT;
+	struct worktree **worktrees = get_worktrees();
+	int i;
+
+	for (i = 0; worktrees[i]; i++) {
+		if (worktrees[i]->is_detached)
+			continue;
+
+		strbuf_reset(&path);
+		strbuf_reset(&ref_target);
+		strbuf_addf(&path, "%s/HEAD", worktrees[i]->git_dir);
+
+		if (parse_ref(path.buf, &ref_target, NULL))
+			continue;
+
+		if (!strcmp(ref_target.buf, oldref)) {
+			const char *symref = path.buf + strlen(absolute_path(get_git_common_dir())) + 1;
+
+			/* no need to pass logmsg here as HEAD didn't really move */
+			if (create_symref(symref, newref, NULL)) {
+				error = -1;
+				break;
+			}
+		}
+	}
+
+	strbuf_release(&path);
+	strbuf_release(&ref_target);
+	free_worktrees(worktrees);
+
+	return error;
+}
diff --git a/worktree.h b/worktree.h
index b4b3dda..512855b 100644
--- a/worktree.h
+++ b/worktree.h
@@ -35,4 +35,9 @@ extern void free_worktrees(struct worktree **);
  */
 extern char *find_shared_symref(const char *symref, const char *target);
 
+/*
+ * TODO
+ */
+extern int update_all_worktree_head_symref(const char *oldref, const char *newref);
+
 #endif